var localStorageSpace = function () {
    var allStrings = '';
    for (var key in window.localStorage) {
        if (window.localStorage.hasOwnProperty(key)) {
            allStrings += window.localStorage[key];
        }
    }
    return allStrings ? 3 + ((allStrings.length * 16) / (8 * 1024)) + ' KB' : 'Empty (0 KB)';
};